Heat the oil. Add the cumin seeds. When they darken slightly, add the ginger and garlic and saute for a few seconds, then add the coriander and cumin powders, tomato puree, kasoori methi, cayenne and turmeric.
Stir and cook until the tomato puree darkens and most of the moisture has evaporated.
Add the cooked dal and stir well to mix. If the dal is too thick, add water to make it more fluid-- you want it to be runny but still fairly thick.
Bring the dal to a boil, lower the heat, and let it simmer for another 10 minutes.
Add the garam masala, stir in, and then add the vegan butter and salt to taste.
Sprinkle on the coriander or spring onions, turn off the heat, and serve hot with some rice or naan.